The end product of building any port is to create packages. pkg_delete(1) only deletes packages, not the object files created when building the port. If you did not run some variation of:

#make clean

...following building, all object files & any other intermediate file will still exist in /usr/ports/pobj. Subsequent attempts to build with make will find that the timestamps of any object file and/or any other intermediate file is still newer than the source, so there is no need to recompile. Linking, though, may still occur at the end.

Thanks Ocicat! that's well explained !!
* I lways do a 'make install clean' .. is it the same as when doing 'make install' then 'make clean' , afterwards ?
* I still have stuff in pobj .. is it safe to remove it ?
Thanks so much

Thanks Ocicat! that's well explained !!
* I lways do a 'make install clean' .. is it the same as when doing 'make install' then 'make clean' , afterwards ?
* I still have stuff in pobj .. is it safe to remove it ?

Yes. /usr/ports/pobj contains the extracted source code and any generated files from a port build. These files can also be deleted via “make clean”.

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Many thanks to the forum regulars who put time and effort into helping others solve their problems.

Most applications in the ports tree create and/or depend on a network of other packages. make clean will only clean the working directory of the primary package being built. Section 15.3.6 of the FAQ discusses a number of other make targets which clean other parts of the /usr/ports/pobj subdirectory. Reading the ports(7) manpage is also advised.